The real zeros of the derivatives of cylinder functions of negative order

An improved underlift assembly is provided for attachment to a vehicle. The improved underlift assembly comprises a support arm coupled to the vehicle. A base is coupled to an end of the support arm, a boom base is pivotally attached to the base at a first pivot point and a boom is pivotally attached to the boom base at a second pivot point. A first actuator is coupled to the support arm and the boom base. The operation of the first actuator pivots the boom base with respect to the support arm. A second actuator is coupled to the boom base and the boom. The operation of the second actuator pivots the boom with respect to the boom base. The first actuator is used to position the boom during lifting operation, and the second actuator is used to position the boom into a folded rest position.